
import java.util.Scanner;

class Fatorial {

    public static void main(String[] args) {
        Scanner entrada = new Scanner(System.in);
        int i = 1, fat = 1;
        int n = entrada.nextInt();

        while (n>0){
            fat*=n;
            n--;
            
        }
        System.out.println(fat);
    }

}
